The elderly should play computer games to keep their brains sharp, new findings by scientists suggest.

Psychologists discovered that playing video games exercised the mind and improved memory and alertness.

It also reversed "cognitive" decline making the brain more agile, allowing it to carry out and switch between tasks more quickly.

Previous studies have shown that elderly brains improve during the playing of video games but this is the first to prove that the benefits remain for weeks afterwards and can transfer to everyday tasks.

The findings support the growing industry of computer games marketed at the elderly as personified by the advert for the Nintendo DS portable games console featuring Julie Walters and Star Trek actor Patrick Stewart.

The team at the University of Illinois recruited 40 adults over 60 years old, half of whom were asked to play a computer game called Rise of Nations, a role-playing game in which you have to build your own empire.

Game players have to build cities, feed and employ their people, maintain an adequate military and expand their territory.

Both groups were assessed before, during and after the video game training on a variety of tests.

They had to carry out a number of tasks to test their brain power including mathematical sums, visual memory tests and carrying out several different tasks simultaneously.

The researchers found that training on the video game did improve the participants' performance on a number of these tests.

As a group, the "gamers" became significantly better – and faster – at switching between tasks as compared to the comparison group. Their working memory, as reflected in the tests, was also significantly improved and their reasoning ability was enhanced.

To a lesser extent, their short-term memory of visual recall was better than that of their peers, as was their ability to identify objects.

Professor Art Kramer, an author of the study published in the journal Psychology & Aging, said that the study proved for the first time that video games were beneficial for the elderly.

"This is the first such study of older adults, and it is the first to find such pronounced effects on cognitive skills not directly related to the skills learned in the video game," said Prof Kramer.

He said that the study seemed to back up the claims of video game makers such as Nintendo that their brain testing software could help to keep elderly brains active.

"I believe that the Nintendo wii has already become popular in retirement communities – and strategy-based games my also be a reasonable and enjoyable way to help maintain, and perhaps even improve a number of cognitive abilities that often show declines with ageing," he said.

"Older people tend to fare less well on things that are called executive control processes," Kramer said. "These include things like scheduling, planning, working memory, multi-tasking and dealing with ambiguity."

"This is one mode in which older people can stay mentally fit, cognitively fit. I'm not suggesting, however, that it's the only thing they should do."